The long-term goal is to develop photochemical decontamination (PCD) methods for the inactivation of infectious pathogens in blood products. We have previously developed a prototype PCD system for platelet concentrates which utilizes treatment with long wavelength ultraviolet radiation and 8- methoxypsoralen with preservation of in vitro platelet function. The purpose of this Phase II study is to develop novel quality control assays with which to optimize the PCD process. The specific objectives are: 1) To develop simple, rapid polymerase chain reaction (PCR)-based assays to evaluate the efficacy of PCD methodology. 2) To demonstrate the inactivation of additional pathogens in platelet concentrates, including HIV-1, HBV, HCV, CMV and Yersinia enterocolitica, without affecting in vitro platelet function. Inactivation of these pathogens is crucial in transfusion medicine. 3) To optimize the PCD treatment conditions so that the method will be feasible for use in blood banks. In Phase I of this study, we have demonstrated the overall feasibility by correlating the inhibition of PCR amplification of genomic DNA sequences with the biological inactivation of HIV-1 in platelet concentrates. The new information which will be obtained from Phase II of this study will be crucial for the ultimate Phase III commercialization of the PCD technology.